Design, Fabrication, and Test of a Low-Cost MEMS-Based Sun Sensor

Abstract

Based on outstanding characteristics of MEMS technology, modern space missions are looking for putting it into practice. Sun sensors are key components in the Attitude Determination and Control Subsystem (ADCS) of spacecraft and satellites. This system requires high precision sensors for controlling the orientation of the vehicle in the desired direction and this can be done by means of a great source of energy, the sun. Focusing on a simple and low-cost fabrication approach the detector has been designed for a field of view (FoV) of ±70°. The working principle of designed sensor is based on differences of currents generated in sensing layers. For having a p-n junction the silicon was doped by phosphorus in 850°C by POCL3 in a container that Ar passes through it on p-type silicon. Afterward, the ITO contacts are deposited by flow of Ar with rate of 200 sccm for about 40 min. By considering geometrical aspects, the detector was developed by placing three MEMS chips, based on a specified lay-out, close to each other. In the maximum FoV the output voltage of the sensor was shown to be 2V.